Handheld device having ultrasonic transducer for axial transmission of acoustic signals

Abstract

A handheld stylus having an elongated housing, a writing and drawing implement disposed within the housing and including a tip extending through an opening at an end of the housing where ultrasonic waves radiate therefrom and are used for determining a position of the stylus; and at least one ultrasonic transducer disposed within the housing. The transducer may be a cylindrical piezoelectric transducer having a holder and a cylindrical piezoelectric film spanning between at least two spaced apart cylindrical surfaces of the holder, or a flat transducer having a diaphragm, and a piezoelectric material disposed on a surface of the diaphragm.

1. A stylus comprising:
 an elongated housing defining an internal bore and having an opening at an end thereof that communicates with the internal bore; 
 a writing and drawing implement disposed within the bore of the housing, the implement having a tip extending through the opening at the end of the housing; and 
 a transducer disposed within the bore, the transducer comprising:
 a holder having at least two spaced apart cylindrical surfaces; 
 a cylindrical piezoelectric film spanning between the at least two spaced apart cylindrical surfaces of the holder; 
 an outer electrode segment disposed on an outer surface of the film; and 
 an inner electrode segment disposed on an inner surface of the film; 
 
 wherein the transducer radiating acoustic energy substantially along a longitudinal axis of the stylus in response to an excitation voltage applied to the film via the electrode segments such that the radiating acoustic energy propagates along the bore toward the end and exits at the opening. 
 
   
   
     2. The stylus of  claim 1 , further comprising a conical reflector disposed external to the opening, the tip of the implement extending through the conical reflector, the conical reflector responsive to the radiating acoustic energy for redirecting the radiating acoustic energy at an angle substantially perpendicular to the longitudinal axis of the stylus. 
   
   
     3. The stylus of  claim 1 , further comprising a cover spaced from the outer surface of the film, the cover including a flange restricting propagation of the radiating acoustic energy along a propagation path defined along an exterior of the film. 
   
   
     4. The stylus of  claim 3 , further comprising a reflector disposed at an end of the transducer for redirecting the radiating acoustic energy toward the opening of the housing. 
   
   
     5. The stylus of  claim 2 , further comprising a reflector disposed at an end of the transducer for redirecting the radiating acoustic energy toward the opening of the housing. 
   
   
     6. The stylus of  claim 1 , further comprising a reflector disposed at an end of the transducer for redirecting the radiating acoustic energy toward the opening of the housing. 
   
   
     7. The stylus of  claim 1 , wherein:
 the at least two spaced apart cylindrical surfaces comprising a plurality of spaced apart cylindrical surfaces; 
 the film spanning between at least two pairs of the plurality of spaced apart cylindrical surfaces of the holder; 
 the outer electrode segment comprising a plurality of outer electrode segments; and 
 the inner electrode segment comprising a plurality of inner electrode segments. 
 
   
   
     8. The stylus of  claim 7 , further comprising a conical reflector disposed external to the opening, the tip of the implement extending through the conical reflector, the conical reflector responsive to the radiating acoustic energy for redirecting the radiating acoustic energy at an angle substantially perpendicular to the longitudinal axis of the stylus. 
   
   
     9. The stylus of  claim 7 , further comprising a cover spaced from the outer surface of the film, the cover including a flange restricting propagation of the radiating acoustic energy along a propagation path defined along an exterior of the film. 
   
   
     10. The stylus of  claim 9 , further comprising a reflector disposed at an end of the transducer for redirecting the radiating acoustic energy toward the opening of the housing. 
   
   
     11. The stylus of  claim 8 , further comprising a reflector disposed at an end of the transducer for redirecting the radiating acoustic energy toward the opening of the housing. 
   
   
     12. The stylus of  claim 7 , further comprising a reflector disposed at an end of the transducer for redirecting the radiating acoustic energy toward the opening of the housing. 
   
   
     13. The stylus of  claim 1 , wherein the excitation voltage has a frequency which has a wavelength in a propagation medium, wherein about half of the wavelength is more than a width of each of the electrode segments. 
   
   
     14. The stylus of  claim 13 , further comprising a drive circuit for sequentially applying the excitation voltage to the electrode segments of the transducer. 
   
   
     15. The stylus of  claim 1 , further comprising a drive circuit for sequentially applying the excitation voltage to the electrode segments of the transducer. 
   
   
     16. The stylus of  claim 7 , wherein the excitation voltage has a frequency which has a wavelength in a propagation medium, wherein about half of the wavelength is more than a width of each of the electrode segments. 
   
   
     17. The stylus of  claim 16 , further comprising a drive circuit for sequentially applying the excitation voltage to the electrode segments of the transducer. 
   
   
     18. The stylus of  claim 7 , further comprising a drive circuit for sequentially applying the excitation voltage to the electrode segments of the transducer. 
   
   
     19. The stylus of  claim 1 , wherein the holder is a defined by a section of the implement which is disposed within the bore. 
   
   
     20. The stylus of  claim 2 , wherein the holder is a defined by a section of the implement which is disposed within the bore. 
   
   
     21. The stylus of  claim 5 , wherein the holder is a defined by a section of the implement which is disposed within the bore. 
   
   
     22. The stylus of  claim 6 , wherein the holder is a defined by a section of the implement which is disposed within the bore. 
   
   
     23. The stylus of  claim 1 , wherein the holder restricts propagation of the radiating acoustic energy along a propagation path defined within an interior of the film. 
   
   
     24. The stylus of  claim 7 , wherein the holder restricts propagation of the radiating acoustic energy along a propagation path defined within an interior of the film.